import fs from 'fs'

fs.readFile('./txt/a.txt','utf8',(err,data)=>{
    console.log(data)
    fs.readFile('./txt/b.txt','utf8',(err,data)=>{
        console.log(data)
        fs.readFile('./txt/c.txt','utf8',(err,data)=>{
            console.log(data)
        })
    })
})